Contact lenses use multiple approaches to reduce aberrations

By applying wavefront diagnostic technology to contact lens production, manufacturers aim to reduce patients’ higher-order aberrations.

Contact lens models currently on the market or in development use a variety of approaches to reduce higher-order optical aberrations in contact lens wearers.

Some lenses address patients’ spherical aberration by using an aspheric surface, an approach that is analogous to aspheric IOLs or to wavefront-optimized excimer laser treatments. Others use each patients’ unique wavefront profile to create custom contact lenses, in a process analogous to customized corneal ablation.

All of the lenses are based in some way on the use of wavefront aberrometry, and all are designed to improve vision and contrast sensitivity by reducing patients’ higher-order aberrations without surgery.

This article reviews products either available or in development that either take individual aberrometry measurements into account to provide a customized lens for each patient or that use an aspheric surface to reduce the spherical aberration present in the average eye.

Definition lenses

Optical Connection currently offers a lens with an aspheric surface designed to reduce spherical aberration. It is soon to introduce a customized product that will be based on each patient’s aberrations, according to Vincent S. Zuccaro, OD, FAAO, president and chief executive officer of the company.

“For nearly 4 years, Optical Connection has marketed the Definition lenses featuring our proprietary patented aberration control,” Dr. Zuccaro said.

Rather than using a single aspheric surface with a changing power curve, the Definition family of lenses use an aspheric surface that changes for each lens power, according to Dr. Zuccaro.

“We did wavefront measurements of patients at every power and used that information to develop a unique aspheric surface for each power,” Dr. Zuccaro said. “Practitioners have reported that this has given a number of specific benefits to patients, including enhanced contrast sensitivity and improved visual performance in varying light conditions.”

The company will soon launch the custom-driven Definition WaveTouch lens, which will be “a truly individualized soft contact lens,” Dr. Zuccaro said.

Physicians will be equipped with a set of specifically designed diagnostic lenses for patients to wear during aberrometry readings, he said.

“These measurements will record lens and pupil positioning data, as well as the patient’s individual measurements, and then be transferred electronically to our manufacturing facility at Optical Connection. There, the identical lens used on the patient is selected and put into the WaveTouchProcess,” Dr. Zuccaro said. “A point-by-point correction is performed on the lens to give the patient a truly individualized contact lens based on their wavefront aberrometry map.”

Company officials said they expect the customized lenses to become available in the second half of this year.

SynergEyes W

The SynergEyes W is a wavefront-customized lens that is currently in clinical trials. SynergEyes also manufactures four lens products with Food and Drug Administration marketing clearance featuring a hybrid design that combines a high-Dk rigid gas permeable center with a soft hydrogel skirt.

Jerome A. Legerton

Jerome A. Legerton, OD, MD, MBA, FAAO, chief technology officer and executive vice president of SynergEyes, noted that, although the products with market clearance, called SynergEyes A, M, KC and PS, are not wavefront guided, they provide some control of aberrations.

“They provide some higher-order aberration correction without being a customized lens simply because the lenses have a rigid center that will neutralize any anterior corneal aberrations,” Dr. Legerton said.

The company’s wavefront-guided lens is the SynergEyes W. Dr. Legerton described the fitting technique in an interview.

“You apply one of our diagnostic lenses and do two things simultaneously; one is to measure the residual lens eye aberration, and the other is to measure the registration error,” he said. “One must demonstrate on an individual eye that the lenses have orientational and translational stability. The nice thing about the SynergEyes product is that the hybrid lens has very little movement.”

Registration marks on the lens are captured when the aberrometry measurement is taken, Dr. Legerton said.

“In the past we could write a prescription on a prescription pad, and that could go to an alternative source for sourcing the lens,” he said. “In this case, the practitioner can’t even write the prescription. It would take pages of code to write it. Rather, the prescription is the byproduct of both registration and aberrometry output data.”

The SynergEyes W combines the fingerprint of the lens with the registration adjustment, creating a new mathematical cutting file, he said.

“Every eye is different. This is not one-size-fits-all stuff,” he said. “That would be like making an orthotic for your shoe and mass-producing it. It’s either for your foot or someone else’s.”

C-Vue Aspheric Single Vision lens

In February, Unilens launched the C-Vue Aspheric Single Vision lens, which features a wavefront-assisted aspheric design, not individually customized.

James A. Muse, OD, began fitting the C-Vue Aspheric Single Vision lens after it was released to the market this year. He said the lens is ideal for patients with low-level astigmatism or early presbyopes.

“It does decrease spherical aberrations,” Dr. Muse said. “I have found it works well on patients who might have a problem with their night vision. They generally have less complaints with their night vision with this lens.”

Dr. Muse said there is a wide range of patients who will benefit from the use of this lens.

“Monovision patients driving at night are less symptomatic with this lens,” he said. “They might have fewer glare symptoms with this lens that has wavefront technology. Also, early presbyopes benefit with some limited near-point correction inherent in the aspheric design.”

PureVision lenses

Bausch & Lomb also has an aspheric contact lens that corrects for spherical aberration, the PureVision Silicone Hydrogel.

“It’s not wavefront-guided per se, but it is a wavefront-enhanced lens, in that it allows us to correct for spherical aberration,” Paul Karpecki, OD, said.

The average patient has about 0.15 µm of spherical aberration, Dr. Karpecki said. To compound that, as the power of contact lenses increases, more spherical aberration is induced, he said.

“What makes this lens unique is that for each power, the spherical aberration correction is adjusted based on what would be induced, as well as the inherent spherical aberration in our optical system,” Dr. Karpecki said. “‘Wavefront-optimized’ is probably the best term.”

Patients will notice an improvement in their quality of vision, he said, and many comment specifically on an improvement in night vision secondary to the improvement in spherical aberration with these lenses.

For Your Information:

• Vincent S. Zuccaro, OD, FAAO, president and chief executive officer of Optical Connection, can be reached at 3315 Almaden Expressway, Suite 25, San Jose, CA 95118; 408-265-8644; fax: 408-265-8639.
• Jerome A. Legerton, OD, MS, MBA, FAAO, chief technology officer and executive vice president of SynergEyes Inc., can be reached at 2232 Rutherford Road, Carlsbad, CA 92008; 760-476-9410; e-mail: jlegerton@SynergEyes.com; Web site: www.synergeyes.com.
• Paul Karpecki, OD, can be reached at Moyes Eye Center, 5844 NW Barry Road, Suite 200, Kansas City, MO 64154; fax: 913-681-5584; e-mail: paulk-vc@kc.rr.com. Dr. Karpecki is a paid consultant for Bausch & Lomb.
• James A. Muse, OD, can be reached at 5400 Southwest College Road, Suite 106, Ocala, FL 34474; 352-622-3937; fax: 352-861-1177; e-mail: museumeyecare@earthlink.net.

• Optical Connection, maker of the Definition WaveTouch, can be reached at 3315 Almaden Expressway, Suite 25, San Jose, CA 95118; 888-556-6567; fax: 408-265-8639; Web site: www.opticonnection.com. SynergEyes, maker of the SynergEyes lenses, can be reached at 2232 Rutherford Road, Carlsbad, CA 92008; 760-476-9410; Web site: www.synergeyes.com. Unilens, maker of C-Vue Aspheric Single Vision lens, can be reached at 10431 72nd St. North, Largo, FL 33777; 727-544-2531; fax: 727-545-1883; Web site: www.unilens.com. Bausch & Lomb, maker of the Purevision Silicone Hydrogel, can be reached at 1400 Goodman St., Rochester, NY 14609; 585-338-5212; fax: 585-338-0898; Web site: www.bausch.com.

• Daniele Cruz is an OSN Staff Writer who covers all aspects of ophthalmology.